如何在没有for循环的情况下编写以下八度代码？

Question

对于以下八度代码段:

stepTerm = zeros(3,1);
for i = 1:3
  stepTerm(i,1) = some97ElementRowVector * some97by3Matrix(:,i);
end

是否可以在没有for循环的情况下编写上面的代码？

Answer 1

怎么了？

stepTerm = (97ElementRowVector * 97by3Matrix).'; 

？

在MATLAB上,

clc
N = 1e6;    
a = rand(1,97);
B = rand(97,3);

tic
for ii = 1:N
    stepTerm0 = sum(bsxfun(@times, a.', B)).'; 
end
toc

tic
for ii = 1:N
    stepTerm1 = (a*B).';
end
toc

max(abs(stepTerm0 - stepTerm1))

给

Elapsed time is 12.114381 seconds.
Elapsed time is  1.827436 seconds.
ans =
    2.4869e-014